Precipitated calcium carbonate (PCC) is manufactured on a commercial scale for use in a variety of industrial, cosmetic and pharmaceutical products. Slurries of precipitated calcium carbonate, such as used in oral care compositions, are susceptible to microorganism contamination. To reduce the amount of viable microorganisms, a preservative, such as aldehyde, can be added to the slurry. For example, U.S. Patent Application Publication No. 2009/0088483 discloses combinations of a dialdehyde (such as glutaraldehyde) and a formaldehyde-releasing agent, such as (ethylenedioxy)dimethanol. Unfortunately, these preservatives have their limitations. Glutaraldehyde, for example, is unstable at alkaline pH, and is therefore ineffective as a long-term preservative for this kind of material. Furthermore, some bacterial strains metabolize formaldehyde (see, for example, Di Maiuta et al. (2009) International Biodeterioration & Biodegradation 63:769-777), permitting bacterial growth even in a treated PCC slurry.
Thus, there is a need for improved preservation ingredients for use in precipitated calcium carbonate containing compositions.